diff --git a/backend/app/schemas/chargepoint.py b/backend/app/schemas/chargepoint.py
index bf95642..2493315 100644
--- a/backend/app/schemas/chargepoint.py
+++ b/backend/app/schemas/chargepoint.py
@@ -8,6 +8,8 @@ from app.schemas.connector import Connector
 
 from ocpp.v201.enums import ResetEnumType, ResetStatusEnumType
 
+from app.util.encoders import decimal_encoder
+
 class ChargePointBase(BaseModel):
     identity: str
     is_active: bool
@@ -32,6 +34,7 @@ class ChargePoint(ChargePointBase):
 
     class Config:
         from_attributes = True
+        json_encoders = {Decimal: decimal_encoder}
 
 class ChargePointPassword(BaseModel):
     password: str
diff --git a/backend/app/schemas/chargepoint_variable.py b/backend/app/schemas/chargepoint_variable.py
index 19200eb..f0a3543 100644
--- a/backend/app/schemas/chargepoint_variable.py
+++ b/backend/app/schemas/chargepoint_variable.py
@@ -4,6 +4,8 @@ from uuid import UUID
 from pydantic import BaseModel
 import enum
 
+from app.util.encoders import decimal_encoder
+
 class AttributeType(enum.Enum):
     ACTUAL = "Actual"
     TARGET = "Target"
@@ -52,6 +54,7 @@ class ChargepointVariable(BaseModel):
 
     class Config:
         from_attributes = True
+        json_encoders = {Decimal: decimal_encoder}
 
 class ChargepointVariableUpdate(BaseModel):
     value: str
diff --git a/backend/app/schemas/meter_value.py b/backend/app/schemas/meter_value.py
index 7a0343e..99f6945 100644
--- a/backend/app/schemas/meter_value.py
+++ b/backend/app/schemas/meter_value.py
@@ -5,6 +5,8 @@ from typing import Optional
 from uuid import UUID
 from pydantic import BaseModel
 
+from app.util.encoders import decimal_encoder
+
 class PhaseType(enum.Enum):
     L1 = "L1"
     L2 = "L2"
@@ -55,3 +57,4 @@ class MeterValue(BaseModel):
 
     class Config:
         from_attributes = True
+        json_encoders = {Decimal: decimal_encoder}
diff --git a/backend/app/schemas/session.py b/backend/app/schemas/session.py
index b6a320b..07b98a1 100644
--- a/backend/app/schemas/session.py
+++ b/backend/app/schemas/session.py
@@ -8,4 +8,5 @@ class Session(BaseModel):
     name: str
     last_used: datetime
 
-    model_config = {"from_attributes": True}
\ No newline at end of file
+    class Config:
+        from_attributes = True
\ No newline at end of file
diff --git a/backend/app/schemas/transaction.py b/backend/app/schemas/transaction.py
index d50ccad..0188f91 100644
--- a/backend/app/schemas/transaction.py
+++ b/backend/app/schemas/transaction.py
@@ -5,6 +5,8 @@ from typing import Optional
 from uuid import UUID
 from pydantic import BaseModel
 
+from app.util.encoders import decimal_encoder
+
 class TransactionStatus(enum.Enum):
     ONGOING = "ongoing"
     ENDED = "ended"
@@ -50,6 +52,7 @@ class Transaction(BaseModel):
 
     class Config:
         from_attributes = True
+        json_encoders = {Decimal: decimal_encoder}
 
 class RemoteTransactionStartStopResponse(BaseModel):
     status: RemoteTransactionStartStopStatus
diff --git a/backend/app/util/encoders.py b/backend/app/util/encoders.py
new file mode 100644
index 0000000..fbdec8d
--- /dev/null
+++ b/backend/app/util/encoders.py
@@ -0,0 +1,22 @@
+from decimal import Decimal
+from typing import Union
+
+def decimal_encoder(dec_value: Decimal) -> Union[int, float]:
+    """Encodes a Decimal as int of there's no exponent, otherwise float.
+
+    This is useful when we use ConstrainedDecimal to represent Numeric(x,0)
+    where a integer (but not int typed) is used. Encoding this as a float
+    results in failed round-tripping between encode and parse.
+    Our Id type is a prime example of this.
+
+    >>> decimal_encoder(Decimal("1.0"))
+    1.0
+
+    >>> decimal_encoder(Decimal("1"))
+    1
+    """
+    exponent = dec_value.as_tuple().exponent
+    if isinstance(exponent, int) and exponent >= 0:
+        return int(dec_value)
+    else:
+        return float(dec_value)
\ No newline at end of file